Soft Lump Under Middle Of Head.

I have been doing stretches with weights for the past few months and just noticed a soft lump under my middle back of the head. The part that faces you. Almost looks like there is no ridge anymore between the shaft and head in the very middle. Is this normal progress? It’s been a week and it’s still there. Doesn’t hurt and its not discolored. Just looks like maybe the skin is stretched there or something. Any idea’s?