G.S.
Same with me. I have a 5 month old who has been drooling, gnawing and mouthing for 3 months. My pediatrician said that it was her teeth moving into her jaw. Now I have read the her Salvia gland are developing and getting ready. He recommended letting her gnaw and mouth things. My Daughter didn't fuss however but she drools like a banche. Now she is older and eating cereal and still mouths everything. We found that a clean finger message works for her. It really seems to help with her pain. I also have invested in plastic backed Bibs which have really saved a lot of clothes.
Good Luck