As was mentioned, tight calves can cause Achilles issues. It could also stem from a tight plantar fascia. Use a roller or other similar torture devices to try to loosen up both areas. Another possible contributing factor can be tight hamstrings. Do some good stretching but not too aggressively so you avoid damaging your muscle tissue. If you can, try to make it to a few yoga classes. Do standing forward bend pose and sitting-head-to-knee pose (focusing on trying to lift your heel off the ground for a great stretch on your calf). Also, try some Tiger Balm for good measure.
