Hi Zahra,
Even a small cold will cause ferritin to rise and this has absolutely nothing to do with iron load. The body sequesters iron in the serum ferritin when it becomes necessary to deprive viruses and bacteria of the iron that makes them thrive. In this situation, the ferritin reading has nothing to do with any added iron load. Of course, as long as he is getting blood and not yet chelating, his ferritin is bound to rise, even if the IP6 is slowing the iron absorption. I don't see this as a problem since he will be starting Exjade in 4 months. Even though it's best to take IP6 on an empty stomach, the main consideration is to not take it with protein foods, so you can experiment with how to best administer it, as long as it isn't mixed with milk. Any type of juice or water is fine and even a snack is OK as long as it's not protein as this will diminish the effects of IP6.
Wheatgrass will not raise Hb in everyone as it does seem connected to the person's ability to produce fetal hemoglobin and this is definitely not equal in all and is related to genetics. However, I do believe wheatgrass is useful in strengthening the immune system and also raising energy levels, so I do recommend it even if there is no change in Hb.