Hi, thanks for writing to HCM.
Generally, a 2 month old achilles injury
will not cause any problem while walking on flat surface.
Based on your symptoms (pain and discomfort while climbing stairs), I suspect either a complete or incomplete rupture of the achilles tendon.
There is nothing you can do by yourself.
Consult an orthosurgeon to ruleout any injury to the tendon.
Hope this helps