What Causes Red And Tender Lump On The Outside Of Fibula?

I have a slight lump on the out side of the fibula. The lump is on my left leg but only appears after running. There is a smaller lump on my right leg but doesnt not affect me. The lumps doesnt hurt besides the fact that it feels like theres pressure on them and they somewhat ache. The lump is tender and slightly red. Yet the lump only appears after I run, should I be concerned?