19 weeks & abnormal lump on bottom of my foot?

So this is my first pregnancy. I'm 19 weeks and yesterday, I find a strange lump on the bottom of my foot. It's more towards the heel, but not in/on the heel. It's probably the size of a small grape. It feels hard inside. It's not sore unless I walk around for a while or if I stand too long.

I be wondering if anybody else has had this and what it might be? I saw some not so scary things it could be and some bleak things it could be and I'm freaked out.

I have a doctor's appointment Tues. but I would really appreciate the feedback, thanks!
Answers:    i think its call bercitus (sp?) it a heel spur. it will go away with foot rubs lol

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