Hi.. Welcome to HEALTHCARE MAGIC.. As per your complain and the symptoms of difficulty in opening mouth wide along with white patches inside mouth and having a history of tobacco chewing points towards Oral submucous fibrosis causing reduced mouth opening along with Leukoplakia that causes white hyperkeratotic [ increased production of keratin]patches over inner cheeks, tongue, inner lips etc.. Both these conditions are Pre-cancerous in nature and if care is not taken it can turn into Oral Cancer.. Oral submucous fibrosis causes formation of thick fibrous bands under the mucosa of cheeks and causes atrophy and blacking of mucosa leading to reduced mouth opening as well as burning sensation on taking even little spices.. The white hyperkeratotic patches are most probably Leukoplakia and is due to continuous irritation inside mouth.. You should immediately take him to an Oral Physician and het evaluated along with a thorough clinical examination and Biopsy of the white lesions.. The physician can advise you to apply a combination of steroid and hyluronidase injections directly over the fibres under the mucosa.. Antioxident like Lycopene is advised. Mouth opening exercises like opening mouth under pressure, blowing cheeks etc can be demonstrated.. For Leukoplakia Retinoids [precursor of vitamin A], multivitamins and anti-oxidant can help.. Hope this information helps.. Thanks and regards.. Dr.Honey Nandwani Arora.