It could also be from stress. I had that happen to me. One time it lasted from November until the following April. I was throwing up at least once a week. The Dr's couldn't find anything physically wrong with me but once I left my stressful job, it only happened twice.
So you might want to watch the situation and then get it checked out if it doesn't appear to be a bug.
kat
Me-53(and learning!) S24, S21, D18, D17 Just keep swimming, Just keep swimming. Dory