Can there be any self-treatment for tendonitis in my achilles?

Rest: Resting the area can be your best friend. Icing and nsaids are also of benefit.

Achilles Tendonitis: Achilles tendinitis which is stretching the tendon where it inserts on the heel. Try wearing a heel lift in your shoe or a slight heel to relax the tendon from its insertion. Ice, rest, topical irritants like icy hot or bengay can help too. If it doesn't get better visit your local podiatrist for further evaluation and treatment. Possible need to ankle brace, walking boot or physical therapy.