Stop eating, or significantly reduce, sugar and carbohydrate intake. Basically go on keto or similar anti-inflammatory diet.
I would also suggest taking Quercetin, known for its anti-inflammatory properties.
https://www.amazon.com/gp/product/B0797DQTVZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
This really may offer you great relief.
Thorne Research - Quercetin Phytosome - Exclusive Phytosome Complex for Antioxidant and Allergy Support - 60 Capsules https://www.amazon.com/dp/B0797DQTVZ/ref=cm_sw_r_apan_glt_fabc_2ZKN8CV0P7BJZ6RK12Z7?_encoding=UTF8&psc=1
Ugh, what an ordeal. At this point - in addition to making sure you're not vitamin D deficient, I might consider trying Hydroxychloroquine + Zinc, though unsure how effective it is in long haulers.
Check this out: https://twitter.com/gummibear737/status/1283840177497088001?s=20
Most of the doctors reporting success with Hydroxychloroquine (HCQ) are combining it with Zinc (and azithromycin in many cases), while most of the large-scale studies on the drug have excluded zinc, which is strange.
HCQ works as an 'ionophore' - allowing zinc to tunnel through the plasma membrane into cells it would otherwise be unable to enter, disrupting virus replication. As many have noted, this appears to be most effective when administered early in the disease, and is a coin toss for more advanced cases.
https://www.sciencedirect.com/science/article/pii/S0306987720306435
HCQ + Zinc would be ideal to start as soon as symptoms appear, but since HCQ is in short supply (and prescription only), there's an alternative compound derived from plants called Quercetin which appears to be an effective zinc ionopore, according to a 2014 study. Its efficacy in treating COVID-19 is currently unknown so treat this as speculative. In theory it could be combined with Zinc to achieve the same results as the HCQ combo.
You can find it here: https://www.amazon.com/gp/product/B0797DQTVZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
And Zinc here: https://www.bulksupplements.com/products/zinc-citrate-powder?variant=29386490904687
More information:
https://www.youtube.com/watch?v=W9YFXo84lCk&feature=youtu.be
https://jvi.asm.org/content/78/20/11334
DISCLAIMER: I'm not a doctor, so do your own research and speak with a medical professional. Also, dosage will vary. Doctors have been prescribing 200 mg of HCQ 2x / day for 10 days + 220mg of zinc once/day for 5 days, which is the same dosage as this study (one I've been able to find which actually includes zinc): https://clinicaltrials.gov/ct2/show/NCT04370782
Oh and if you get worse, I would consider asking to be treated with intravenous Vitamin C, which has been shown in Chinese studies to reduce mortality and shorten duration in the ICU, and is currently the subject of several ongoing studies.