any doctors willing to donate a little of their knowledge to me please?

My derm put my on doxycycline for my acne. 1.5 hours after the first dose I got a golf ball sized lump above my left collar bone. 4 days later it's about half the size and barely visible anymore. Could it be linked to the antibiotic? I'm so scared everything I google says cancer or lymphoma. I have no other symptoms. Someone tell me there's a bigger chance that it's NOT cancer. Already did an ultra sound. Awaiting the results. Possible ct scan next week.