This is really a bad idea using the same running shoe for more than 3 month. I am not sure but that might be the cause of your calf and shin pain. If you did take proper care in initial stage then he may have overcome this problem easily.
Not only you but also each of every runner usually faces this type of problem including me. Anyway I would like to share my experience with you the way I got rid of from this problem. Read all of my advice carefully and follow those cautiously:
• If you have been running in your shoes for over 3 months, you should consider replacing them. Running shoes take stress off your legs by cushioning every step you take. A good pair of shoes that fits well can help a lot.
• Try to find softer surfaces to run on such as a grassy park or a dirt trail. Running on pavement creates extra stress on your legs. Don't switch back and forth from hard to soft during the same run.
• If your shin splints have gotten to a point where they hurt even when you're not training, then you need to take at least a couple days off, maybe a week or two.
• Don't run longer than your shins can take. Pay attention to how your shins feel and when you can sense pain stop running and go home. Some days this may happen after you've only run a mile; other days you'll last much longer. Eventually your shins will get stronger and you'll be able to run as long as you'd like. When your shins need rest, try another activity like biking or swimming. That way you can still stay in shape while not hurting your shins.
• What about your weight? Are you a over weighted runner. Lots of adults in their 20's begin to gain weight and don't realize that this is why their shins and knees can't take as much pounding as they used to. Guess what? Your eating habits have finally caught your metabolism and it's time to start eating less. If you eat less and continue running, you are bound to lose some weight.
• Do feet exercises. If you don’t know then follow this way. Tap your feet up and down while you're sitting down. When you're in bed, move your toes back and forth. Exercises such as these help build the muscles around your shins which will support your shins more while you're running.
• Start every run with a shin splint exercise. This is very important for you. You'll go 25 paces angling your feet/ankles in 6 different positions. There are 3 toe exercises and 3 ankle exercises. Jog lightly, on your toes with your toes pointed forward for 25 paces. Then turn your toes in (pigeon toed) and jog, still on your toes for 25 paces. Now turn your toes out and jog on your toes for 25 paces. Now land lightly on your heels with your toes pointed up. First straight forward. Then pointing up and inward, then up and outward. After about 2 weeks, your shin splints should minimize or disappear.
• Stretch your calf muscles as you are also suffering calf pain. Tight calf muscles can contribute towards many lower leg injuries including shin splints. Try stretching the calf muscles, ensuring you target both Gastrocnemius and Soleus, several times a day. Hold each stretch for 20-30 seconds and repeat 2-3 times.
• Get some sports massages. If possible. Sports massages are fantastic for treating many sporting injuries. They are especially useful for loosening the calf muscles and breaking down any scar tissue.
• Count the number of steps you run in 20 seconds. You should have 30 steps in 20 seconds. If you have more than 30 lengthen your stride. If you have less than 30 shorten your stride.
• If shins are painful, stop right away. Training through it makes it worse and thus they will take longer to go away. It’s a serious pain!
• Try to land on the center of your foot with every step.
Now see, all of those tips are easy to follow. Just try to practice those in proper way so that you would not face any pain in your lower leg in future.
