Swelling and pain aren't normal conditions. So, cut your runs in half and see if the swelling stops. If not, cut the distance in half again, and so on. You may be doing more than your body can handle. When you find a distance you can run with no swelling, make small (less than 10%) increases in distance and stay at each new level until you feel comfortable with it. If the swelling returns, go back to a previous distance without swelling and run that for a few weeks then make an increase.
There was a time when miles and miles were the runners training diet, but my understanding is that more about training at max working pressure for 15 to 20 mins three times a week. With 10 minutes warm up and cool down you are looking at at least 3 sessions of about an hour per week to maintain your current form. One way of achieving this is by using a fartlek method of running fast for 30 secs and then recovery jog for 4 mins 30 secs. You can play around with the fractions and speeds but consider 1 min and 1 min 30 secs in your routine with 4 mins and 3 mins 30 secs recovery jog respectively. If injury is still an issue then it is not because you are running too far, so seek medical help.
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