Solange Knowles has opened up about her struggles with numerous autoimmune disorders, saying that it can be a “debilitating, confusing and lonely” experience.The singer-songwriter and actor, who is the younger sister of Beyoncé, wrote about being diagnosed with postural orthostatic tachycardia syndrome (PoTS) when commenting on a post by musician Shaun Ross.In an Instagram post, Ross explained that he had been diagnosed with PoTS after suffering with long COVID.According to the NHS, PoTS “is when your heart rate increases very quickly after getting up from sitting or lying down, often making you feel dizzy or lightheaded”. It adds: “There’s currently no cure, but it can be managed with changes to your lifestyle, or sometimes treatment with medicines.”Replying to Ross’ update, Solange wrote: “Sending u so much love and strength Shaun and to all in the comments struggling with the debilitating, confusing, and lonely symptoms of POTS!”The singer went on to confirm that she had been diagnosed with PoTS, Sjögren’s syndrome and mast cell activation syndrome (MCAS) in 2018.