I'd go and see a physio if you can ... at least he'll make sure you never start off at 70lbs again
warming up with light weights and a 5 minute jog might have helped
being fit is a long term effort and you can't do it all in one session whatever weights you lift
hell i'm only on 3 sets of 70lb and I've been doing weights for a year ... give your body a chance to adjust, unless you like pain
good luck though! hope it's getting better