Knee and Achilles Tendon Pain?

I've had this knee pain since September and basically it's like 1/2 inch below my knee caps, I went to the doctor for it in around October and the doctor said it was just inflamed from soccer practice. However, I've had to live with this pain for a long time, sometimes it hurts constantly but it's basically always there. Then, about a month ago my Achilles tendon has started to hurt, and it hurts to walk even now, I try to stretch it out but to no avail. I told my dad he says it's nothing but I'm starting to get worried as soccer season comes around in a few months and I don't want to have knee pain and Achilles tendon pain.