If want my advise mate:
Go to a physio and get them to test all your muscle groups for strength from shoulders to foot.
Get them to look at your running and walking.
Here is a few simple things you can do to check yourself:
Lay on you left hand side. Bend your left knee (ensure the thigh is in a straight line), and straighten your right leg. Make sure there is a straight line from you head to your right leg and keep your hips pushed forward. Lift your right leg as high as you can making sure you hips stay straight forward and your right leg is still straight. Get a friend to apply pressure on your right leg pushing your leg downwards. If this is done fairly easily it means weak gluts. You can test this at different leg heights. Turn over and do the over leg.
Stand on one leg lift the over leg off the floor. On the leg you are standing on raise yourself on your toes (calf raise) do this going right to the top as many times as possible. If you cant do 50 with ease you have weak calves. Failure on this test occurs when your body starts over compensating for the stress on you calf.
I went to physio every week for 2 months and my physio was doing all sorts of tests on different muscles to find out which were weak and which were strong.