Hi C....my first thought is definitely to get help. ANY help, even if it's just someone to watch him for an hour so you can clear your head. I know how it feels; my now 3 year old cried like that...EVERY single day, most of the day. It turned out he had a milk allergy, and he was probably having tummy aches from the small amounts of dairy that were in some of the Gerber 2nd foods. Is he acting at all like he has tummy trouble (acting gassy, vomiting, etc.)? I would definitely call your pediatrician and see if there is some advice he/she has for you. If Tylenol helps, it MUST be relieving some kind of pain...so maybe he could help you find out what pain it is relieving (maybe it is teething...) and give you some advice on what you can do.
Just remember that there are a lot of resources out there for moms...if your b/f or husband works all day, seek help elsewhere...in your friends, relatives, the pediatrician, maybe your city has a family resource center that could offer support...ours does. Good luck!!