We have covid in the house, bought in by my younger son we think. Last Thursday he tested positive and remains so today..day 6
His symptoms are nothing more than a cold.

My other son is the confusing one. He’s had close contact with his brother, in a car etc and last Friday the day after his brother he started to feel bad. No cold symptoms but he has the chills ( no fever) is tired and exhausted, his body aches, loss of appetite, feels sick and has diarrhoea. He has a very minor cough and sore throat.

After a day of feeling awful, he started to feel better until by Sunday he was back to,normal. This morning, he’s gone right back to the beginning, all the symptoms are back.

Confusing thing is despite doing LFT each day he has persistently tested negative. He’s ticking 80% covid symptoms, minus the cold symptoms.
The co incidence is too great that we have covid in the house and he’s ill too but I just don’t know. Can it go away completely then come back? Why is he testing negative? We just are not sure whether he has it or not.