Hi, i'm facing some problem in opening my mouth and chewing food, have developed this condition for the last 3 days. im also using ulcer gel but nouse

Hard to diagnose: Hard to diagnose on this forum. This could be some type of TMJ problem due to your occlusion or some sort of trauma. You don't clarify whether you are using the ulcer gel for an ulcer or for the chewing problem. As i mentioned above there are too many unknown variables. Probably best to be examined by a dentist to start the process of diagnosing and treating the problem you have.

Acute TMJ: You have acute onset inflammation or dislocation of the TMJ (temporomandibular joint). I recommend soft diet, anti-inflammatories (nsaids), and warm moist heat massage. If it continues you will need to te a dentist who is familiar with treating this disorder.

Inability to Open : The condition most common for an inability to open fully, especially if it is painful, is either the trismus in an injured muscle, likely the masseter or medial pterygoid or it's a closed lock of the TMJ whereby the disc is dislocated in front of the jaw bone blocking its opening.