Hi I did review your concern I would advice you not to get worried and get the bump evaluated The best initial investigation should be to consult a surgeon and ask for a cytology diagnosis of the bump where they insert a needle in the bump and extract fluid if any and cells and examine them under microscope. When we know the pathology and cause we can then relate it with your other problems and also may be investigate for your lightheadedness and pulsating thumb separately i hope this helps Let me know if you have any more questions or concerns Wish you a very healthy life ahead.