I wouldn't start with although.
'Having experienced a certain level of joint pain (can you say what this is due to?) since xxxx/over a long period of time I have recently a deterioration in my condition. From xxxx to xxxx I was taking painkillers on a daily basis and symptoms showed no improvement.
Then...
Although I have always had a certain amount of joint pain, over the period from Christmas I realised I hadn?t had a day when I hadn?t taken multiple painkillers; this escalated rapidly and I saw the GP (16th Feb) who ordered blood tests (24th Feb) and changed my pain medication.
I discussed the results at an appointment on 4th March, and my medication was changed again. On 15th March I saw the GP again he has proposed reactive arthritis as a diagnosis and he referred me to a rheumatologist who I will see on 7th April. However this diagnosis may change as my brother has been diagnosed with Rheumatoid Arthritis for some years now.
My symptoms include severe joint pain in multiple joints, long bone pain, and lack of power in my hands & feet. The problems with my hands are causing difficulties with typing and writing. The pain is causing concentration difficulties and distraction.
The medication is causing some disorientation, inability to concentrate and some memory issues.
Would then suggest.... I hope this is a temporary state if affairs while I adjust to this medication however I am finding it difficult to cope with the demands of daily life (which include - give details of other mitigating circumstances) as well as the additional demands of this course. This means I have not been able to devote my full attention to my studies.
I wluld suggest giving more details if you're going to put this in: In addition I am having counselling as I already have several long-term conditions and this is a further one
Then your final apology for the lateness is fine.