I've got red slashs lines under my armpit, there seems to be a few bit of hard little yellow bits (size of ant) in armpit. Its v

The yellow small ant like sized things are just throughout the armpit hair. I also have 2 mole kind of things under the armpit. The red slash lines are across the whole armpit area. Its very itchy and painful, any ideas what this is and what I should do?

I do know that I sweat alot (puberty) but its started to calm down/stop now, not sweating alot (I think its just nerves/confidence at times).  I use Boots Anti Presperant for men, been fine with it.

This all started a few days ago.