I am needing to loose weight But do to poor health limited ways to exercise. Allergic to Diet pills?

I have tried Slim Fast, Dexatrim, Hydroyxcut, The Grapefriut Diet. The pills made me deathly sick. Due to Degenerative Bone Disease and Degenerative Hip Disease Walking or Riding a Bike are OUT OF THE QUESTION. I am allergic to the Chlorine in the Pool Water.It blistered my skin worse then any sunburn. Cost almost $300 dollars to heal my skin. went to the pool as a teeneager and ended up with Chemical Burns in my lungs and on my Skin.Tried walking this summer and made it maybe 1/4 mile on a flat 1/2 mile flat walking trail. And spent 2 days in bed with sever pain in my back and hips. Had to have help to just get out of bed to go to the bahroom. Now I have tendonitis of the Achillies Tendon of my foot. I know I would feel better if I lost 100 pounds. I tried a stationary bike and the seat hurt my pelvis and my hip bones so bad I could scream. So now I am at a loss on how to get execise. I was going to try Walter Arobics but afraid of the Chlorine in the Water. Any suggestions would be great.