It is common to get problems with the Achilles tendon when running and playing sport. It can be very difficult to cure the problem but here are a few tips.
Don't do nothing - few tissues of the body get better with complete rest, So cycle, swim, row etc. and increase the stretching. The best regime to cure an Achilles tendon problem involves eccentric loading (loading while the muscle and tendon are lengthening not shortening) such as standing on your toes on a step and lowering the heel, holding for a few seconds then coming up with the weight on the other leg. This will slowly stimulate the tendon to heel over 2-3 months if repeated twice daily, but caution is needed at first to ensure that more damage is not caused. Sometimes the tendon is too weak to stand the strain and needs careful supervision. Go to a clinic where there is at least a doctor and physiotherapist (sports injuries need team work rather than just one therapist!) and ask about eccentric loading exercises.
But be patient! Local massage can stimulate the blood supply and aid healing. Injections can help a bit but only alongside appropriate exercises, and surgery is very much the last resort. Physiotherapist's electrotherapy (ultrasound, laser etc.) can make a little difference but the main part of treatment is what you do yourself to stimulate the tendon - there are no short cuts!
Point to remember : Increase the load on tendons slowly. Don't go mad when starting any exercise regime!