Buy sodium bicarbonate (SB).
Use tea spoon C (4g) with 1/2 tsp SB in water, and wait until reaction finishes.
After it does, taste will be slightly acidic if you didn't put enough SB, slightly salty if you put it too much and neutral similar to mild carbonated water if you did it right (you created sodium ascorbate, ascorbate acid salt, with pH ~ 7, ascorbic acid has pH ~ 5 which is higher then Coca Cola).
This means you can tweak the level of acidity you want.
If this doesn't help, use after the protein rich, carbohydrate low meal.
Its almost certain that you have some digestive problem if you can't tolerate C, like h.Pylory infection. My colegue had it and couldn't tolerate 500mg C without pewking. Now she drinks 5-10g of pure acid without problem.
Alternative way is to use carbonated water and add amount of ascorbic acid you can tolerate.
Remember, smaller & more frequent doses are more beneficial then larger one time doses.
You could also try with Mg-Citrate powder.
And if you still have problems, you will have to buy lipospheric C which is expensive.