How long does it take a cavity to turn into an abscessed tooth? It looks like it's in between my front teeth. When I went to my dentist in february, he didn't say anything about it. My insurance won't cover more than two visits, and my next one is in july

Whenever . Whenever you notice something like this you need to make an appointment. Your reference to insurance covering only two visits should apply to routine exams and cleanings, not emergency situations or problem focused visits in between. Do not wait as a small cavity can get bigger and a big cavity can cause an abcessed tooth. How long that takes varies tremendously depending upon the situation but you don't want to take a chance to find out. Call now!
As . As dr. Scharf mentioned, it is important that you see your dentist right away. The longer you wait, the worse it can become. So something that would only take a simple filling will later need root canal and crown or extraction and replacement. Don't wait and take the risk of getting more extensive and costly treatment. This holds true even to those who do not have insurance since cost of consult and simple filling is nowhere close to the extensive treatment needed once the tooth starts to hurt !
Hold . Hold on! we cannot be sure you even have a cavity. You say your dentist didn't say anything about it. That could be that he missed diagnosing a problem, or it could be that it was just a stain, or a start of a cavity that stopped progressing. You really need to have it checked by a dentist or hygienist to be sure. In the meanwhile, keep it clean by flossing and brushing with a flouride toothpaste.