Another disturbing symptom due to 635 that has only accompanied the rash twice is a very strong sensation of 'knotting' in my oesophagus. It's similar to the feeling of eating a lot of food too quickly and having to wait for it to travel down. It comes in waves, like contractions, and I wonder whether it is the peristalsis of my oesophagus firing unnecessarily. It has woken me from sleep on both occasions and I find that it responds to taking an antihistamine. - by email.