My back hurts

Two years ago I had my first back injury and I'm not sure how it happens. I woke up and I went to my kitchen to have my breakfast.   so when I opened my refrigerator and bend bent down to take get a yoghurt. then When I tried to stand up, and I felt a pain in my back and I couldn't stand up at all. My family was at my home and they took me to the hospital. I had a second degree lumbar sprain and the doctor said that it happened because I was attempting (or "had attempted) to carry something heavy. I remembered that at my job (or "at work") I was installing and configuring big boxes and I had to move them to from one place to another. It Aalso Ccould have happened be in the gym when I was doing some leg exercises without a protection like a special belt. I didn't work for a month while I was resting and doing rehabilitation (or "...while I was rehabilitating.")

You did an excellent job, Gerardo.  I wish I could do half as well in Spanish!

My Bback Hhurts (in English, capitalization rules for titles are different: http://grammar.yourdictionary.com/capitalization/rules-for-capitalization-in-titles.html)

Two years ago I had my first back injury but and I'm not sure how it happensed. I woke up and I went to my kitchen to have my breakfast so and when I opened my refrigerator and bendt down to take a yoghurt pick up some yogurt, then I tried to stand up and I felt pain in my back and I couldn't stand up at all. My family was at my home and they took me to the hospital. I had a second degree lumbar sprain and the doctor said that it happened because I was attempting to carry something heavy. I remembered that at my job I was installing I installed and configuring configured big boxes and I had to move them to one place to another. Also Could be It could also have happened in the gym when I was doing some leg exercises without a protection like a special belt. I didn't work for a month while I was resting and doing rehabilitation.

Muy bien! Cuidale con los tensos de los verbos y también el vocabulario.