I am drinking muscle milk twice a day to replace meals and taking a multivitamin, fiber supplement, and triple tea fat burner. why do i feel jittery?

Low blood sugar?: There is no obvious reason for you to be jittery that i can see. It is possible however, ? That your blood sugar could be dropping and making you hypoglycemic.

Stimulant; pyridoxin: Triple tea fat burner contains caffeine, which can cause jitteriness in some people, depending on the quantity. Muscle milk contains pyridoxine as do multivitamins; so you may be getting too much of this b vitamin, which is associated with peripheral neuropathy when too much is taken at a time. Try eliminating the multivitamin for a week or 2 to see if condition resolves.