Hello David and welcome to the forum
You made my blood run cold, arrrrggghhhh, trying weight lifting with a bad back, it hurts me just thinking about it.
I think the best thing is for you to ask the doctor to refer you to a physio, these good people will give you a set of exercises that are safe for you to do, they teach you to do them correctly.
Also you dont have to do strenuous exercises at all, if you just fiddle with your toes and fingers, while you are sitting or lying in bed, its some kind of gentle exercise, I was going to say that you could move your arms around, do loads of exercises with them, flexing, straightening, sideways, in front of you, above your head but no, DONT do that please if you have a neck injury now as well. Then there are so many chair based exercises with your back supported, maybe you can do any of these, I am sure that you and a good physiotherapist can work out an exercise regimen that is safe for you to do.
PLEASE DONT try any more exercises in the meantime, till you got seen by a professional, you might hurt yourself even more.
All the best to you
Karen