So its not progressively getting worse or better? At this point, it would be good to either increase the dosage of the antibiotics (double it) for a few more days to see it it helps or to drain it/treat the tooth. It seems the antibiotics are only stabilizing it.
Any medical or health problems that may affect your immune system? At 150mg, your antibiotic is more bacteriostatic (meaning its not at a high enough dose to kill bacteria but enough to prevent it from worsening). They sometimes prescribe this dosage to allow the immune system to work and clean the infection. Also, since its a lower dose, you get less side effects.