The history of Gutka chewing is suggestive of a disease called Sub Mucous Fibrosis (SMF). This is a condition where the tissues get fibrosed and that is the reason there is difficulty in opening the mouth. Avoid spices, supari, smoking and gutka. See a good dentist and they will start you on treatment for SMF. This disease needs treatment and should not be ignored as it has a chance of progressing further to a non-reversible state.