That sucks bigtime man
Hey not to put the scares on you, or be a know-all or anything, but definitely get it checked for second opinion by a physio or someone.
I was told by a doctor that I'd sprained my calf at beginning of last summer. I walked on it for a week before seeing a physio who told me it was a ruptured achilles
I've got my fingers crossed for you that its a sprained calf like you say, and that it'll be on the mend and you be back riding real soon.