Many times plantar fasciitis is caused by tight muscles in the calves. The muscles in your calves attach to the heel via the achilles tendon. If the muscles are tight they pull excessively on the heel which can result in achilles tendinitis as well as the type of heel pain that you are experiencing. I regularly massage my calves using a lacrosse ball to seek out any sore spots commonly known as trigger points. When you find them you'll know because it is likely that they are quite painful. The amazing thing about trigger points is you don't know you have them unless you go looking. My approach is to sit on a hard surface table like a laminate table. Place the ball mid calf and place your arms behind you. Raise yourself up a bit and roll your calf over the ball slowly. When you find the sore spots pause at that site for 30 sec to a minute until the soreness eases. Proceed in small increments searching out other sore spots and pause on them as well. I then basically roll the whole length of the lower leg from the achilles up to the knee. If a lacrosse ball is too painful try a tennis ball to start out with. Over time the soreness should dissipate as the health of the tissue improves. I would be very careful about stretching at this point because stretching a tight muscle is counterproductive. Step 1 is to improve the tissue and then stretch. As the tisssue improves the pull that is occuring at you heel should dissipate and thus the symptoms should dissipate as well. I think if you go to youtube and search for trigger points calves you might find some further guidance on this treatment. Good Luck.