Hello.
Thank you for your query at DoctorSpring.com
From your description, it seems that you have devloped a canker sore.It can develop secondary to an acute infection ( viral ), stress, or due to injury. You already have a cold and also you have been stressed, and definitely not getting enough sleep. All these are causative factors for canker sores.
I will advise the following medicines for you :
1) Xytee (Metronidazole gel ) to be applied locally on the lesion 3-4 times a day.
2) Chlorhexidine mouth wash, to be used each time after meals ( 3-4 times a day )
3) Tab. Neurobion Forte once daily at bed time for 10 days.
4) If symptoms do not resolve then, after 2 days start
Tab. Triamcinolone 8 mg once daily till symptoms subside.
Hope this was helpful,
Regards.