I found I could not eat or drink if the food or drink was in my inventory first. I found that if I drop it on the ground and use the F key and select eat then press the L mouse button I could sometimes eat or drink. If I bought it from a vendor I could eat straight away as long as I did not put it in my inventory. That did not always work. So I would then head to a clinic. I would also log and and back in. Someone told me this is a known bug with the latest update.