Hey!!! Sorry to hear of your current issues. Doing an ICP test will definitely uncover any chemical abnormalities within your system. The only downside would be the time it will take to acquire results, which will in turn affect how soon you would be able to rectify any issues. Depending on the company used, it could take about 3 weeks to receive results, and now possibly longer due to covid19. Out of curiosity, I actually just mailed out some samples to be tested on Monday (still pending receipt of samples).
Have you checked your power heads or pumps for rust? Have you made any changes to your flow recently? I don’t think the changes made to your lighting schedule would affect your LPS to that extent. Generally, doing a couple water changes could also help if there is a chemical imbalance or elevated pollutants in the system.