Help with weaning my son?

my son is just turning 6 months old. I have been giving him puree veg ect for about 3 weeks now, it's seems very soon after this he developed diarrhea and has had it for about 3 weeks now so far. He used to sleep all night in the last 3 weeks he has been getting up at least 3-4 times a night night crying. He is very irritable in the day time. He is teething at the moment so i no this could be a contributing factor, but i am wondering if maybe the food isn't agreeing with him or something maybe its because he is teething. Has anyone had there child react to food this way before. maybe i should try him with finger foods instead I gave him some toast fingers this morning and some melon to chew on but i was just so worried he was going to choke, i am not sure what to do as i didn't have any of these problems with my daughter. i have an appointment to see a doctor today about the diarrhea.