You could try an anti-fungal cream to see if that helps (the same kind used for athlete's foot).  However, since this problem has been getting worse over time, I think you are going to need a doctor's help to identify exactly what is causing the problem and get the right medication.  Using the wrong medicine could make it worse.  Find out if your community has some sort of free clinic where you might get treated.  You can also use a credit card to pay the doctor if you don't have enough money left in this month's pay check. 

There are health insurance policies specifically for young people in your situation that are comparatively inexpensive, so as soon as you can, look into getting one of those.  If you can't get insured, you might want to consider setting aside at least a little from your pay check each month to start your own health savings account so that you have the money to pay for a doctor's visit when you need one.  I know the whole health insurance issue is a difficult one for young people just starting out, but it's important that you have a plan for seeing a doctor when necessary so that little problems don't turn into major health issues.