Hi, I've heard that clitoris changes during persons lifetime but idrk... I have the same problem, I think it's because of masterbation...
Hmm. Well, if it were me, I'd loosen the pants, and also chart when it happens. Is it right after your period, for example? Then mention it at your next ob/gyn exam with all the data. If it happens in relation to your period, I would wonder if it's BV.
When it happens, especially if it's happening at a time when you won't have access to a doctor for a while to ask, try a sitzbath in a solution of epsom salts, or a weak solution of white vinegar in water. Do it every night for a few nights, and see if that helps.