Try diluting milk and doing a foliar feed. See if the droopiness improves. You can foliar feed with milk to fix a calcium deficiency. The reason I say to do it with diluted milk is that the stoma on a plant's leaves act like a human's lungs. Snorting drugs into your lungs makes them enter your system immediately. The same thing happens to a plant when you spray stuff on the underside of the leaves.
Foliar feeding is the quickest way to resolve a
nutrient deficiency. It's also the quickest way to OD your plant, so start small and apply more doses as needed.
If you let your plant bear fruit before you fix the droopiness you will get blossom end rot.
PS
I did a water change and added a diluted Ca Mg supplement and my plants have bounced back bigtime. I was having the same problem you currently are but not as severely.