what are red bumps/pimples all around armpit & side

sometimes i get big swollen red bumps like a bite or boil,those are usually on my armpit around where i shave,and when its touched it hurts.and the big boil like ones ive gotten them on my breasts also!?but then i also get smaller red bumps like pimples or something that come back as soon as i think they go away.and those range from being on my armpit up halfway under my arm and then All down my Side!!why?!i think it all started when i started shaving my armpits and putting deodorant on. for a while i sweat so bad when i was younger that it was almost unhideable and embarrasing.and when i really started noticing i had to try to fix it,its just gotten worse over the years. i don't know if this is a disease but i think its time to go to the doc otherwise who knows how much more it could spread..Any Help!?!?