Any suggestions for cardio when have Hamstring Tendinitis (1 year) and it still hurts.?

I was diagnosed with Hamstring Tendinits a year ago, and since have not healed completely. I am now very limited to my cardio regiment (previous elliptical, treadmill, treadclimber, bootcamp fanatic), not to mention my lower weight training. I have since lost lower body strength, lost muscle and gained fat (previous 21% BMI - 5'5" @ 132lbs; presently 140lbs - ? BMI afraid to know). Other than a leaner diet, what fat burning exercise do you suggest? I know I can walk, but it just takes so long to burn the calories I used to burn in just 30min, now it takes more than hour.... Help... Discouraged