Hi again!  Yes, there are multiple possible explanations and we have a saying in medicine called "common things are common".  In a healthy 22 year old, it's unlikely that you would have something as serious as the thing you are worried about.  It's not impossible, but unlikely.  Again, the best way to find out, and to help yourself stop worrying, is to get this investigated properly by experts.

Hello!  This is Dr. Biali, in response to the question you asked.  I'm going to speak very generally to protect your confidential information, in case a friend of yours reads this etc.  I would say that most likely there is a less scary explanation for your symptoms, especially if you're young and healthy.  Has your doctor referred you to a specialist for further investigations?  That might be a good idea, if it's not already in process.  Good luck!