Hi Samirsmummy,
If you feel happier having your baby on a routine, as I did, then by all means give it a go.
The Gina routine is fine IF you adopt it in a flexible manner - don't beat yourself up if it doesn't go exactly to the letter.
The Baby Whisperer's EASY routine is another good one, and is more flexible. It encourages you to structure your babies' day in the same, repetitive order, so that your lo knows what is coming next, but it isn't driven by exact times, and it removes the 'clock watching' element.
Maybe have a look at them both, and see which one more closely resembles the routine he was on before.
I think your temporary loss of routine is less down to the jabs and more down to the fect that he is getting older! My DS is nearly 9 months now, and several times, our 'routine' (I use the word loosely) has gone to pot for a few days, and a new one emerges, with perhaps more awake time between sleeps, or shorter naps etc.
I'm sure a new one will evolve in time, but I see no harm in encouraging him down that route by trying one of those two, as long as you stop and try something else if it clearly isn't working.
IIRC, at that age, my DS was awake for about 2 hrs between naps, and slept for 3/4 - 1 hr at a time until bed at 7 ish. That routine wasn't out of a book, it's what he wanted, but it meant he was very predictable so that was good enough for me.
It does sound as if he may be overtired in the evenings if he's crying a lot.
Like others have said, try to have a set wind down routine to bed time, maybe bath, feed and cuddle then curtains shut, lullaby toy on, into bed and lights out ( or whatever works for you)
I'm sure you'll be back on track in a few days, whatever you do - I remember many times thinking 'Oh no, it's all going wrong', only so find it sorted itself out in a day or two, and my ds had just grown up a bit!!!
Good luck whatever you decide.