If you're using infant's Tylenol (concentrated drops) an average baby under 6 months should get .8 in the dropper every 4-6 hours. So as long as you're not giving him more than .8 every 4-6 hours, he should be fine. Overdosing on Tylenol, however, can cause liver damage, so you want to measure it properly and obviously not give him too much. I have given both my daughter's properly measured Tylenol since they started teething and they are both healthy and well. When he turns six months, with your pediatrician's permission, you can start also giving him infant's Motrin. If you alternate Motrin and Tyelenol (Motrin you give every 6-8 hours, Tylenol every 4-6) you should keep his pain pretty under control. Teething hurts. I see no reason not to give medications when you can, as long as you dose it properly.
He will absolutely get used to the rolling. Part of his aggravation is that he can't roll back from where he's rolled himself to. Fortunately, the aggravation will probably help him work at and learn how to roll himself back to where he wants to be. I went through this with both of my daughter's, and it ended in a few weeks when they finally learned how to roll both from front to back and back to front. Until then, we just had to deal with the lack of sleep.
To deal with that, I made sure I tried to nap when the baby napped, and tried to bring in help every so often (a sitter, my mom, a friend) to watch the baby while I caught some rest. At times like this, don't worry about the house, the dishes, the laundry or even work--if you work, you can take a sick day--you need to take care of YOU, as well as the baby.
This will pass. Really. Soon it will just be a distant memory. Take care of yourself.