Too much liver canned food ???

My cat loves Fancy Feast Classic liver and chicken, but I am wondering if it could be unhealthy to feed it to him more than a couple times a week?  Is it too rich for his digestive system perhaps?  He got sick last night and today, which he doesn't usually do -- a pasty brown glob and some brown liquid today.  I will watch him closely.  Thanks.

The classic pate versions of fancy feast are usually recommended but sometimes cats do develop allergies to chicken. Does he get sick with any other food? Maybe try feeding another type for a fews days and if he is still getting sick taking him to the vet just to make sure there isn't something else going on. Here is a great video on cats and vomiting: