I am having pain in my ankle what should be the possible causes.

Several Causes: It can be due to several causes and if it persists it should be checked.We can not tell you what it is due to in your case without history and examination.It can be due to 1trauma causing sprain or a fracture 2osteoatrthritis 3gout 4achilis tendinitis or rupture 5bursitis 6pseudo gout 7septic arthritis 8rheumatoid arthritis 9tarsal tunnel syndrome 10stress fractures so get it checked.

Ankle : As stated it needs to be evaluated and x rays taken. See your podiatrist for help.