Abcess or something else?

For the last several months, I have had reoccurring lumps of sorts on my gums. They started about a day after my last dental visit, where I had x-rays and all of the other usual dentist checkup-y things done and they didn't find any abscesses or anything like that. I do have 2 teeth with cavities in the back of my mouth (one on each side) but the dentist didn't think either of them were THAT bad, but should be filled as soon as possible, though due to me not having any insurance he didn't see any reason that with proper personal dental care it couldn't be taken care of later. Anyway, I have these lumps on my gums, and everything I have ever read about abscesses (whatever) says that they cause pain, usually immense pain, but mine don't cause any pain at all. They're not even a tiny bit sore, and they go away intermittently but then raise back up, usually in the morning when I wake up. Any ideas as to what this is or how to go about treating it? I went on a cycle of antibiotics back in September when I first was terrified I had dental abcesses, but they didn't go away. My GP thought that maybe they weren't dental abcesses or a dental infection... but wasn't sure what they were since there was no pain and they didn't go away with antibiotics.
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This is quite difficult to diagnose via your description, could you give some description of position + colour of these lumps, do they discharge pus or anything similar? If nothing showed on the x ray it sounds to me like they're relatively superficial (just on the surface of the gums), which wouldn't immediately suggest they would cause any problems. Medication can often affect the condition of the gums, however its best you check with your dentist/GP that they aren't a sign of any underlying condition you may have. The fact they go away intermittently is again rather strange, how much does the size vary? Sorry I couldn't answer your question more specifically, Et.
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