Sorry you had that experience, that doc sounds like a jerk.
As for the actually cross-reactivity, according to Pharmacists Letter it is:
- approximately 0.1% for patients without skin test-confirmed penicillin allergy. (most patients according to owlegrad)
- approximately 0.1% for those with mild reactions to penicillin.
- approximately 2% for patients with a positive penicillin skin test.
Personally I would not call for that. But I also think it is never wrong to err on the side of caution and would respect someone who did call, as long as they are informed about the relative risk involved.