You got to get to know the main reason you r getting fever. Check online with your physician if any UTI or infections there rule them out first. In many cases some arthritic conditions might show up as fever and also get an xray of the spine and few blood tests like urine culture CBP and maintain a diary of how fever is presenting as and discuss with ur physician. Make a note if there has been a loss of weight and appetite..

Take treatment for fever . For that consult ENT surgeon or ur family physician. Pain in back may be because of PIVD . You have not mention what aggrevates ur pain and region of refeered pain. Rest is the best remedy.

First do treatment of your fever,do static abdominals,static back exercises,bridging Dnt take hot fermentation as you hav fever & dnt apply ice as well,once your fever will subsided start with mild hot fermentation at ur painful area

First step is to get treated for your fever. Once fever subsides you can take treatment for your back pain. Since your pain is from 22nd March it could not be muscle strain. As the pain is sharp and radiating you need to Avoid bending activities, lifting weights, prolonged standing, sitting without back support etc.

You have to treat  fever first, Take rest

To fever medication firstly and spine  and so spine extensions

Consult online if that's disturbing your functional activity so that tele assessment would help to locate whether its muscular or pathological involvement. As of now, stretch hamstrings (refer youtube) & apply hot water pack.

If u are having back pain n radiation in the leg, it can be coz of bad posture of sitting. So plz sit in upright position on a good chair.  Avoid sitting on bed. U can use mild hot water pack on lower back n hip where pain is occurring. Do interval walking at home. U can also use any pain gel like volini or dynapar or any pain ointment u have at home for pain relief. Don't bend forward or lift weight. Don't do any exercise at the moment coz it can errupt the pain. Once pain will subside u can contact a physiotherapist online on practo to know some good back exercises.

Get some anti viral medicines by physicians.

Hai , how Long is the fever for you as now it is April I hope ur fever might be subsided am I right if so then coming to your back problem ur saying it is radiating so it will be a neurological pain only kindly do have hot fermentation to the back apply some volini gel and sleep using a pillow at the back of knee so that u relax ur back muscle while sitting n chair have some pillow too at the back . Kindly visit a physiotherapist once the quarantine period is over