Sorry I has been some time since I posted.
Probiotics are for gastrointestinal and immune function health. They help to deccrease the growth of undesirable gut microbes, improve nutrient absorption, neutralise intestional toxins and eliminate parasites. A healthy bf baby has perfect gut flora but bottle-feeding, antibiotics, poor fibre diet, junk food etc can kill off our probiotic bacteria and increase the population of undesirable microorganisms.
Re: inablility to digest cereals, a baby's digestive system at 6 months is not really ready for concentrated carbohydrates such as rice, potatoes, wheat and grains,oats and barley etc. and they dont do much in the way of nutritional value anyway. If cereals are causing reflux elimate them until at least 9 months, I would avoid wheat based products for even longer. There is enough evidence around that suggests introducing wheat too early can lead to sensitivities later in life.
Remember that the aim of solids between 6-9 months is to get your baby accustomed to taking the spoon, textures and tastes. Dont be concerned about introducing everything immediately, they have the rest of their life to try everything. Start a new solid and give it consistently for at least 4 days (7 days is better).
PS have you thought about getting a Chiropractic assessment for the reflux?