Hi.. Thanks for the query.. I have noted your complain of having a sore bump on the left side of the roof of mouth with colour slightly lighter than the remaining mucosa. Well, first of all just relax as it is not cancerous as it can be due to a number of common causes. It can be an abscess caused due to infection as you are already having a recent history of cold.. Other common reason for this lump can be a mucous cyst or Mucocele formation. So jumping directly to cancer is not a good idea, as cancerous lumps are mostly painless.. The lump will hopefully start regressing in size with just topical remedies like to relieve pain you can apply Choline Salicylate or Lignocaine containing oral gel. You can also apply an antibiotic ointment like Chlorhexidine containing or Metronidazole containing ointment. Gargling with salt water will definitely help.. Also to prevent irritating the with your fingers or tongue again and again. lump avoid touching it. Chew a Vitamin C pellet daily as it helps in improving overall immunity. The lump will start showing signs of regression in a week but in case if it does not get better then you should consult an Oral Physician. Hope you get well soon.. Thanks and Regards. Dr.Honey Arora.