Well, when we started foods with my daughter we began with Gerber. She would get fussy, even with the cereal, have gas issues, and be an over all miserable little girl. Then we switched to Hipp and Alete baby foods and cereals. No problem ever since. The formula she hates, regardless of what brand. My son had to go through a number of brands and types of formula before we found the right one, which turned out to be Milk-based formula that contained no lactoses, Soy made him sick. If you think it is just a gassy issue or reflux you should, before trying any kind of meds, go natural with some Bauchwohltee, which you can give a baby as young as 1 week old. You can mix it into the cereal, with breast milk, or give it to the baby alone. It worked wonders with my daughter, even worked when I ate brocoli.
We started my daughter and son on baby food and cereal at 4 months old. Also, the German baby foods have less sodium and taste much better, even to adults than the Gerber and other American brands. Lastly, the veggies are mixed in Alete and Hipp foods, sometimes even with meats starting at the 4 month stage. My daughter won't touch veggies by themselves, but loves them when mixed. She is 6 months and in perfect health as of her apt today.
So, to sum it up, you live in Germany... give the Germans a chance and if it still doesn't work, all kids are different. Some don't start eating baby foods until later than others, or bring it up with your Dr. Oh, and Gute Nacht or Schlaf Gut meals seem to be easier on the tummy for my daughter than other meals and they really do help her sleep better.
Good luck!
My Info: My son is 4 yrs old, daughter 6 months old. Both happy and healthy as can be. I am still nursing my daughter. And we have lived in German 3.5 years so far with the Army.