The main concern with children and medications like that is compliance. From my understanding, it is when they don't take their meds or they skip doses that they become suicidal or aggressive from the medication. It is more a withdrawl thing than the actual medication causing this type of problem. So if you do put him on a med, make sure he takes it daily- and at the same time each day.
There is one anti-depressant that is thought to be "safe" with kids; I believe it is Prozac, but you'd need to double check that. As an adult taking Prozac right now, I find that if I miss a dose, I feel weird that day, but not agressive or suicidal.
As a teen, I was prescribed Paxil. The first week or two was totally bizarre. I literally laid on the couch and stared at the ceiling for about ten days straight. My boyfriend had to actually carry me down the street and put me on his dad's couch so I'd have a different ceiling to stare at for a while. I was a complete zombie at first. I really have to advise to stay away from Paxil for children and teens. That was just a very frightening experience in retrospect. My boyfriend though thy had given me the wrong drug or dose or something and researched it himself.
It does sound like you child is OCD- remember this disorder occurs in varying degrees (my sister is mild/moderate OCD) and many people can learn to cope with their symptoms without medication; however if it is severe enough to be interfering with daily life or life enjoyment or physical safety, then medication might be worth pursuing. As a teen I had obsessive/compulsive thoughts that would not go away- I would imaging someone was in the backseat of my car while I was driving, and I would be unable to tear my eyes from the rearview mirror, watching for someone to pop up in the backseat. Obviously this was a hazard to myself and others. I also had to stop and investigate every dead animal by the side of the road (in case it was still alive and needed help) or in case it had a collar and was someone's pet. I would be pulling over to investigate ambiguous lumps in the road that turned out to be big rocks or wadded up sweatshirts. One winter, I was absoplutely unable to stop myself from pulling over for the same rock every time I went by, since my brain was somehow convinced each time it was an injured puppy, even though I knew full well it was a rock. The Paxil (when it started working,) did a lot to stop those thoughts, or to make them mild enough that I could ignore them.
I was an "anxious kid", afraid of everything. If your son is having trouble enjoying life, by all means, be willing to explore all avenues of treatment, including medications, but don't overlook the benefits of therapy. The RIGHT therapist can be a great help especially if used along with medication. Another thing I found helpful in my younger years battling the anxiety issue, was writing. If your child shows any interest in writing or any kind of art, encourage that however you can. It can be a great relief to release your fears onto a page.
Also, keep seeing different doctors until you find one that you and your son both are compatible and comfortable with. If you are unsure about the diagnosis being correct, seek a second - and third, if necessary- opinion.
I hope some of that has been helpful. I had a miserable preteen and teenage-hood battling anxiety and OCD-type issues, plus major depression. My parents didn't know any better, so I didn't receive any type of treatment until my very late teens when I insisted I needed help. My opinion is that the sooner you can intervene and get your son on a treatment plan, the better. Keep in mind that the first treatment you try may not work, so keep trying until you get the right thing.
HUGS and luck to you and your son.