Likely, you are correct- it's probably from not cleaning and being sweaty regularly. Hygiene is really important, so I'd recommend working on that and seeing if it heals up. Also, it's always best to go see a doctor in person for an accurate diagnosis- an in person exam can't be replaced, so if you don't see any improvement head into your doctor to be sure it's not something that needs a prescription to be cleared up (such as a fungus, etc).