9 month old all of a sudden waking ever 2 hours crying.?

I would try tylenol (although I found motrin works much better and lasts longer!) and see if it helps. I would give it right before you put her down for the night. However you may have created a habit at this point by going in there. She had learned if she crys you'll come and she even gets to go to your bed sometimes. So if the pain relievers do not help, you may want her to cry it out or else you are both going to be very sleep deprived and unhappy- and that is not healthy either!