Hello!
First, I don't think you have "Boils" - It sounds like TRIGGER
HIVES to me which is caused by less sleep, high-blood pressure, and
stress. I would be willing to bet it is trigger hives.
Have you talked to a doctor? - Also in the armpit this is VERY common (my father had the same type of thing) but he was a hard, and stressed worker for a long time. The armpit is a typical and normal trigger-hive area, as well as a lot of places on the body.
I reccomend
VITAMINS daily, some meletonin to help you sleep, and also, perhaps seeing a doctor in person.
You might need to try to RELAX a bit - If possible, take a 10 day AT HOME vacation, even FIVE days.
I hope this helps.
(Also cramping is caused by stress - it can be Ulcers) so keep an eye out on that, and those feelings.
You sound like an over-worked horse that really needs to try to take it easier! You're younger I am sure, and I hate to see us young guys get taken down by stress!
You can fight it!
Good luck, I hope this helps. (But you don't have BOILS, I can 99% promise you that)