Calf pain

Hi! New to the group but hoping to get some input on a problem I’ve been having. I have a been a runner my whole life, but have only recently (past several months) began building u my mileage. I have noticed in the last few months that I sometimes get a deep pain in my lower calf muscles (a problem I have never before had), specifically on the sides of my calves near my shin bone. Normally, the problem will go away after taking a few days off running. But because I’m focused on building my mileage, this is not ideal.

I don’t think the issue is my shoes, and the pain to be pretty unpredictable.

Any suggestions??