I have triplets, too! Mine will be 4 in May. I know it's really hard when they are all sick. I can't even imagine what you are dealing with right now, having to do it all on your own. And it *is * hard to figure out when to ride it out and when to run to the doc.
To answer your first question, I would say to try tylenol/motrin and if it's been a whole day or so and they don't seem to be getting better, fevers going down, etc. to at least call the nurse at your peds' office and see what they think. If it's after hours, most pediatricians have an on-call nurse available to answer questions.
To answer your second question, one day at a time! I'm *still* trying to get it all figured out, and they're almost four. All you can do is just love them, try as hard as you can to meet their needs and realize that you won't be able to meet every single one of their needs and wants. Also, seek out support from friends and family, even if it's just to talk on the phone to someone for a few minutes. Sometimes just a little break like that can help you regain perspective when you are wading through throw-up and tears. Also, if you are religious, prayer helps a lot. You can find support from your church, as well. I wouldn't have made it without the help of friends, family and my church when my kiddos were younger.
One more thing...just so you know, there is a support group for families with triplets and higher in the Valley called Multiple Joys. There are many single moms in the group who I'm sure would give you a lot of good feedback. We have a group on Facebook, and our website is www.multiplejoys.com. Or, you can send me an e-mail at jillymrob(at)gmail(dot)com and I can hook you up with another single MOM with older triplets to help you out.
Best of luck. I know these are trying times, but you'll make it through!!