Calcium deposit on elbow

13 year old has a soft bump about the size of a nickel come up on the elbow, no issues with pain or performance. Pitching coach said most likely a calcium deposit and normally treated with antibiotics. Recommended getting appointment with orthopedic physician. Have made appointment but will be a couple of days. Have been very cautious with pitch counts and follow recommendations. Just curious if anyone else has run across this issue? Thanks