This is so hard, I do sympathise. I too have had a lot of health issues since we got Jess (now 11 months) and it has been very difficult indeed at times.
At 7 months old (have I got that right?) your Alfie is becoming an adolescent with all the 'interesting' behaviour traits of a teenager. The only good bit about it is that the chewing due to teething is about to stop - any time now! There is a second teething phase which is noticeable in some dogs around 10 - 11 months old, but apart from that, the teething is done with.
The annoying bit is that if you do chase after them when they've got something they shouldn't, the thing instantly takes on much higher value for themm, and they also have the added fun of playing 'chase', so they are going to want to do it even more. So chasing is a bit counterproductive. Very hard though, we have both had to become very much tidier.
If Jess does run off with something, we've found the best option is to head very conspicuously in the opposite direction, calling her as we go - going into the kitchen and opening the fridge, making sounds of 'oooh, what's this?'. Jess will follow to see what we are up to, and it is then usually quite easy to swap whatever it is for a little piece of chicken or sausage. (My husband has a theory that she is training us to do this, in order to get more treats out of us. Hmmm....
)
And I would really recommend doing some obedience work, if you can manage it. Jess gets more tired out from this, than from any amount of exercise.