I've made a phlegmy throat for a while now and i've noticed a bitter taste at the back of my throat after drinking water. could the two be related?

Maybe: New throat pain can be from a strep throat infection (antibiotics are needed), a cold or influenza (antibiotics usually not used), or from another cause such as allergies or irritants. Usually, a person sees the doctor if the throat symptom is bothersome, recurrent, or doesn't go away quickly (mainly to check for strep throat). The doctor can also look for a sinus infection.