Jenny, you absolutely should get the lump on the roof of your mouth checked out soon. It could be nothing, or it could be something serious. The fact that you came to this site shows that you are aware that any abnormal area in your mouth needs to be checked. Good for you! Don't wait. An ENT would be an appropriate place to start, and he/she should probably either biopsy the area or get a scan done. If he/she seems mystified, go to your closest cancer center, to the oral and maxillofacial surgery department.