Hi,
I'm sorry to hear you've been having some medical problems while taking Amlodipine. I am not sure what is causing your
frequent urination but it is likely not Amlodipine, since this medication isn't known to have those side effects.
If you have already seen a kidney doctor, I'm sure you don't have an infection, but you may need to see a
urologist to check for any bladder problems like
overactive bladder. As for the itching there are too many causes to list, one cause is Amlodipine but this would be rare.
The most likely cause would depend on if you have a skin rash at all, and only after looking for other causes would I consider blaming it on the Amlodipine. For your
nasal congestion and post-nasal drip, you may have a
sinus infection or just allergic rhinitis; if it is just allergic rhinitis a medication like Cetirizine may help.
I hope that helps. I think it will be important to see your regular doctor and tell him/her clearly about all these problems you've been having, and hopefully you can find some relief.
Hope I have answered your query. Let me know if I can assist you further.