sores or std?

In my inner thighs towards my butt I get these pimple looking sores, they are raised and almost feel like a sist if you push on it.  The only time it hurts is if you put pressure on it.  Sometimes it will have a white head and pop like a pimple, sometimes almost like deadskin will peel off, but after it isn't raised anymore, it will leave a bruise or a dark mark.  It is usually just in my upper inner thigh but they will occasionally show up in different places on my body.  I am not sexually active and never was so I don't think it could be an STD, but Im not sure..

[NDG322]

Could it just be ingrown hairs?