Welcome to HCM!
I read your query in detail and found that you had some lesion in mouth and you were diagnosed with lymphnode abscess
and then more lymph nodes appeared.
I think your lymphnode enlargement has some infective etiology rather than lymphoma
and lleukemia is a rare possibility.Bacterial and viral infections like Infectious Mononucleosis
can be the possibility.
You must get a FNAC done .A complete blood count
along with peripheral smear,leukemia and lymphoma can be ruled out by these simple tests.see an ENT specialist.
I hope this wil help.take care!