im running my first half Marathon and i never use any of energy gel or sport drink 15 days left for half Marathon im from uae i live in (dubai) so i wander what should i buy and when i drink on training and half marathon i run 4 times each week 35 to 40km and 1 or 2 times cycling for 30min im still slow so i maybe missing something im on diet from today so if someone from or live in uae knows about the products in uae would be easy to buy and anyone one could give me advise on which energy gel or sport drink and when and how manny i should get on training day and marathon sorry if its alto to ask i really love running and i want to keep up with it and btw in training when i run 10km on 7 km or 8km i drink little water and within 2 min i feel pain on my stomach and it slow me down or maybe stop for 2 or 3 min how i get use to this pain or how to drink without getting pain?

little about me age 26 male my height 172 weight 79kg body fat 16% i was training in gym for muscles and 20 days ago start training for marathon more jogging and very less lifting.