Quitting after all this time may be very difficult. Besides getting additinal evaluations of things, I think there are two things you should consider. Ask the docs for and Rx strength nicotine subsitute, these come in nasal sprays and also a container like an inhaler. Of course the docs are going to want to give you lesser strength doses as the months progress. Another alternative is a dip made from black tea leaves that has the same nicotine levels as what you are used to. It is called Blue Whale. According to the company it has none of the carcingens that are found in conventional spit tobacco products. Obviously you need to figure out what is going on in your mouth, but getting off the chew an be really hard given the very high levels of addictive nicotine that it has in it.