The pain your feeling is good news for you.
I agree on increasing calcium but, I think the reason why you didn't get any sensitivity with the helimolar is because these types of composite fillings block or stagnate the meridian energy flow through the tooth, check this site out
and scroll down to read about cheap brands of composites.
most people who get composites don't feel any sensitivity after they are placed because of the energy blockage, this is a bad thing because it can result in a disease causing process in a distant body organ. (Chinese Acupuncture says.)
I feel the reason why you are getting a sensitive response from the diamond crown is because this expensive composite does not block the energy flow which is a good thing because the energy can flow freely throgh this brand of composite and it won't endanger any of your body organs to disease.
I had helimolar composites put in as a replacement to Amalgam
and would not do that again. In fact I wish like you I had diamond crown as I was sick and still am now after these fillings where put in. I never had any tooth sensitivity but was cronically ill that I wish I had never had helimolar.
A natural practitioner measured the acupoint flow through my mouth and said the composites are blocking vital flow.
So I think what your feeling is good news even though it may hurt I am sure you will adjust to it. Diamond crown is a very respected filling material and this sensitivity is a good thing because it means all the energy flow or acupoints are working fine. (meaning no disease in distant vital organs.)
I hope you feel better soon, I'd try the calcium, good luck.