Try to take it down with some yogurt or digestive enzymes and see if that helps with the C5.
I like C5 for strength and Cv02 for the endurance, others may have it in reverse, but thats how it is for me.
Also I am going to check to make sure my sanity isn't off course here, but since my last order of Cordygen 5, it was not an enteric coated product. To my knowledge it should be dissolving in your stomach the same as v02 ultra.
have you tried running a candida cleanse lately? this usually cures issues that people see with Cordyceps....especially when they are as potent and pure as anything in the MST lineup.