Q I have a permanently dry throat, which turns to a violent cough whenever I eat, and is worst at night. X-rays have shown nothing. I’m 61 and a nonsmoker. Help.

PB from Leeds

A This is not a lung problem, but one of acid reflux, where stomach acid spills into the gullet, triggering symptoms including coughing. The fact it is worse when you lie down supports this.

Prop the head of your bed up slightly, cut down your caffeine intake as this can make it worse, avoid heavy meals late at night and ask your doctor for a strong antacid called a proton pump inhibitor. If your cough starts to settle, you have your answer.

Q I occasionally suffer from light-headedness and a strange impairment of vision. It’s as if my eyeballs are rapidly moving left and right, resulting in a juddering image that lasts about five seconds. Should I be concerned?

CF from York

A I think you are suffering from horizontal nystagmus – a condition that causes the eye to move involuntarily and continually. This affects around one in a thousand people in the UK and can be hereditary.

It can affect distance vision, sometimes causing clumsiness and tripping, but fine detail is usually not affected. Get an eye test now. For more information visit www.nystagmusnet.org.

Q In January my son’s legs felt “wobbly” between the knee and hip and he was unable to walk far. Blood tests and an MRI scan have all been clear. Now they may perform a muscle biopsy and see him again in four months, which seems a long wait. Could it be circulatory or due to lactic acid build-up?

SH via e-mail

AThis is a complicated case. Your son needs to have the biopsy (where a small sample of muscle is taken), as this will show up any abnormality in his muscle tissue. I doubt his symptoms are linked to lactic acid and if his circulation were responsible I would have expected his whole leg to be affected. Tell his doctor of your concern and see if he can speed up the next tests as these may hold the answer.

All questions are answered by a practising doctor.
To consult Dr Know, e-mail drknow@sunday-times.co.uk.
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