Don't blame yourself. I've been having the same trouble, although my son is more physically aggressive. I've gotten to the point that I just couldn't deal with one more call, email or note from the school and it damaged my relationship with my 5 year old.
First don't ask your Pediatrician they have an answer, medication and they aren't equipped to handle the emotional aspects/side effects of the medication.
Observe your child in class. Then you can teach him and his teacher ways to handle his compulsion to talk, like learning sign language or aggression by avoiding group activities.
In the class room I learned that my son does have impulses he cannot control, but he also has other children goading him and a teacher that doesn't have an tough voice or attitude.
We've struggled with weeks and weeks of daily behavioral reports, stripped him of every belonging and privilege even left him for hours in an empty room and nothing has helped. After one day with him at school I knew what our answer was.
My son is very advanced academically but too emotionally immature for school. I don't want to keep him home so we found a medication to help him control his impulses. We did not be do this through a pediatrician. We have him monitored by a psychiatrist so she can evaluate him for depression or BiPolar when those feelings arise or are triggered by the medication.
We've had a chemical profile and ECG performed on our son. He has the marker for Hemochromatosis therefore supplements are not a solution and there are too many unclassified fillers in Herbal remedies. Pedi-Active caused an allergic reaction.
The Psychiatrist also works with me and my mother to control our BiPolar disorder, we trust her. We know that there is a chemical imbalance in our own brains and we have the knowledge that a regular pediatrician would often discount as worrisome family members.
This is the last resort. We've switched classes twice, schools and he's been homeschooled. The only other thing to do is keep him out of school this year and I'm not willing to do that.
He's been on the mediction for almost a month and it really helps his behavior at school. However, it's designed to wear off after 8 hours and he's back to being loud and wild at home. That's okay though cause we also use a mixture of STEP (Systematic Training for Effective Parenting)
A system for democratic, respectful & practical parenting
http://lifematters.com/step.asp and you might be able to get one of these books through your child's school. We also use
the baskets in The Explosive Child by Ross Greene http://www.ccps.info/ We checked this book out on tape from the Tulsa Library system. You may be able to find it in the OKC system as well.
In addition to all of this we instituted a grading system and the school followed suit. For every hour he is good he gets a bear. For yelling, cussing, saying mean things he gets a mean face and for physical aggression or explosions he gets a beanie kicking a box. I printed those images out on paper from my clip art in MSWorks Word Processing. At first he had to be good 75% 11 out of 14 hours of the time now he's up to 90%. For every hour he doesn't earn a bear he loses something and if there are multiple problems in an hour he loses something for every event. He has an opportunity for earning one thing at a time back by making his goal for the day or getting 6 bears in a row. We also have special bears for making it the whole day. At the end of the week he can cash in his six regular bears for 6 days of good behavior for pizza, presents or playtime alone with us. He can also cash in 6 special bears for extra special activities like a bon fire with dad out on the pool patio, trying to stay up all night, going skating at Granma's work.
I can't say that all days are good but He rarely gets down to the point that he's lost everything but his freedom anymore.
I wish you luck, patience and I would suggest you call Family and Children Services. Driving to Tulsa to see Dr. Herring wouldn't be practical but I'm sure they have someone just as good at an office in the City.