Hi Samar
I think this sounds like an infection. The redness, soreness and smell are all symptoms for this. Treatment is likely to be needed with antibiotics if you can get to a vet with him.
Cathy Wickenden BVet Med MRCVS
Barton Lodge Veterinary Centre
1 Midland Road, Hemel Hempstead, Hertfordshire, HP2 5BH
Tel: 01442 216048 24 hours
[
www.bartonlodgevets.co.uk]