Injuries & Illnesses...man do they ever suck

I'm in need of a bit of help/support here.

In the fall, I was running lots and lots and quit smoking. In December, I got a lung infection and took 3 weeks off of anything that could wind me ... in January, I started running again for 2 weeks before I got pneumonia in February - that took me out of commission again for a few weeks. In March, I started back up to where I was in the fall - running between 35 and 40km/week, walking 15km/week. Then I tore my Achilles tendon in a freak non-running related accident. It seems like every month, my body turns against me.

I am finding any weight I put on my foot is just too much for me - squats, cycling, elliptical are all out of the question since it hurts too much to apply weight. I can't swim because, well, I just can't actually swim (can't afford lessons and am too embarrassed to admit to someone that I can't and have them teach me... I'm also really stubborn when it comes to asking for help).

But, my mind has so much energy and I know I need to burn calories. How can one exercise with a torn Achilles tendon and still get the burn/high from cardio?

I feel like I am getting fatter and fatter by the second because I can't do anything. It feels ****ing terrible.