Hello there ,
Thanks for writing your query,
Appearence of brown sore spots on the gums is nothing but the ulcerated area developed on the gum mucosa due to irritation caused by chronic use of tobacco .
and smoking has many hazardous effects on the oral health as well as general well being so please discontinue the habit .
For ulceration , i would suggest you to go for symptomatic treatment at home like gargling with lukewarm saline water or antiseptic mouthwash like chlorhexidine
Apply oral antiseptic ,analgesic
ointments like dentogel or mucogel topically over the affected area which helps in healing.
start with multivitamin
supplements for 7 to 10 days and vitamin C lozenges will help in resolving the problem.
avoid alcohol , carbonated drinks , tobacco chewing and smoking as these may worsen the area affected.
visit a dentist
and get the examination done , if the symptoms do not subside,
i hope this helps ,