Poor Simba! I posted about this same thing a month or 2 ago. Reggie was doing it. I'd seen him do it on walks before, but when we went camping in June, he did it really bad, several times. It lasted a long time, and scared the crap out of me. I think it might have been related to allergies, as we were camping. He hasn't done it at all since then. Hope Simba is ok!