What Causes Bruise Between Joint Of Thighs?

i have a question, i have this mark ( looks likes bruises and the skin is a lil soft) between the joints of my thighs. on both joints next to the testicles. like, on the joint of the legs n the in side, will u please help me by telling me what this is? maybe growing marks? im 18. i wiegh 180 im 6'2