Welcome. I must say you have come to a superb place for help and information. Emotional support here is the best ever.
Firstly, sickle cell disease is something I can't comment on other than to say my friend has it, and he goes through so much pain. I do know the basics of it, but wouldn't dream of even trying to dicuss it with you, as I am completely in the dark regarding what you must go through with this. I do know that it an extremely painful condition, and I really feel for you with this.
Secondly, I am not a medical doctor but only speak from my own personal experience of being a patient with SLE for most of my life, over 30 years.
Rightyho, flax seed oil I believe is safe to take. I started to use this after my 2 heart attacks and triple bypass. It is a rich source of Alpha-Linolenic Acid -ALA, which is a member of the Omega 3 essential fatty acid family. I was advised to use the Omega 3's, but the fishy taste and so on put me right off. There is no taste at all with the flax oil I use.
It has been researched and shown to be especially helpful for protecting heart and artery health. With this information I am entirely comfortable taking it with my history of heart issues. The capusles I use have a vegetable origin and are competely free of gelatin. As you know at one time the actual capsule that contained the oil or liquid was made from gelatin, a substance of animal origin.
Although flax seed oil is widely used, I would ask your doctor before using any type of health store or herbal product, or indeed any OTC medicines. He/she is the best person to advise you on this. What does one patient good does not necessarily mean it will be ok for you personally. Please take care with this.
I have a haematological disorder alongside SLE. It is APS, Anti Phospholipid Syndrome, or sticky blood. Not all lupus patients have this, and not all people who have it have lupus.
Hope this has helped a llittle.