Pain in the neck, literally!!

I purchased this for my 6 month old daughter, since she likes hanging on the side and I was uncomfortable in her bulky front carrier. I thought it would be a great idea...not so...It was fairly easy to set up and use, a tricky getting her in and out. I walked to the mailbox and back and had a terrible pain in my neck and the strap was cutting my skin. The next day I woke up and my whole side was killing me (mind you I am used to carrying my daughter 7-8 hours a day, so it wasn't lack of excercise as my husband suggested :)
My daughter was only 18 lbs at the time, I could not imagine using this for a 1 year old!!