Lump of sorts in my esophagus

I have a rather bad abscess on the left side of my face, due to grinding my teeth at night. I filed my taxes as soon as I could and when I got my refund, I made an appointment with the dentist. He prescribed Hydrocodon for the pain and Clindamycin HCL for the infection. I already have an appointment to extract the tooth. Here is my problem; I started the medications on Wed ( 02/09/2011) and this morning (02/12/2011), I have what feels like a lump in my esophagus. It's nothing palpable as far as I can tell. It's located directly between my breasts, and feels like I swallowed a bite I hadn't chewed properly. It gets worse if I lie down, making me nauseous enough to run for the bathroom. If I take a drink of something significantly different in temperature than my body, it feels as if it's getting stuck on top of this lump, and goes around it very slowly. There is no pain when I swallow, but this feeling is rather painful and comes and goes. It seems to last for maybe 10 secs or so, and seems to happen about every 2 or 3 minutes. As I don't usually take pills for anything, I'm uncertain as to whether this is related to the medications and something normally expected or something more serious. Does anyone have any ideas?