Teething? + breastfeeding

My is son is 3 months he'll be 4 months in 12 days, and i think he's teething (picture below, area circled) he chews on EVERYTHING, soft toys, clothes, blankets, fingers, his hands, anything. He doesn't use pacifiers (he spits them out) he would rather chew on my finger. But now when I breastfeed he bites down and puts a lot of pressure on my nipple causing it to have a burning, throbbing feeling that can last for about 30 minutes. Is there anything I can do? Has anyone dealt with this? He don't really take a bottle, he has before but started rejecting them for about a month now. Is this teething? I'm a FTM.