What Does Pimple Like Growth On Thigh Indicate?

I have this hard like pimple on my thigh for about 4 yrs now. I noticed it after I had my second son who is now 4 yrs old. It hurts if I press on it or pinch it. It doesn't move like a lump but I feel it's hard. If I squeeze it it forms like a dimple. Should I be worried about this? It looks like it got bigger in time as well.