Stress, excessive grooming & furballs

[Miss Kitty]

Due to changes in work, our MC has gone from having someone with him at home at all times, to having no-one at all. Within 4 days of the change, the following happened to our beautiful MC:
* chronic diarrhea (up to 11 times a night) - sometimes a furball would appear in litter
* throwing up furballs (the same night)
* excessive grooming of his coat
* excessive clingy behaviour when we'd arrive home
* started sleeping in our bed at night
* started grooming my hair at night in bed
* urinating in different places

He wouldn't pass a bowel motion for up to 3 days and then he'd have chronic diarrhea and vomiting on the 4th day. This was repeated for up to two weeks.

The vet visits have:
* done complete bloodwork and test on all organs - all fine
* fecal tests showed some inflammation in the bowel
* urine tests were fine

He was given flagyl for 10 days. After it had run it's course, the symptoms appeared within 2 days. He is now back on flagyl until mid of next week and then back to the vets. Vets are thinking it's either time to treat the hairballs or that he may have a food allergy (but has been on RC MC biscuits and fresh kangaroo meat for over a year now).

Any tips on how to deal with stressed cats (when you can't change what is causing the stress). Also - any ideas on how to help the furballs pass more naturally so he doesn't have chronic diarrhea?

THanks! - any help or suggestions would be appreciated.