His thumb has healed but Jason Day is fighting the latest in a series of health afflictions as he prepares for this week’s US Open.

The 26-year-old has been hit seven times with illness this year, most commonly sinus and throat-related problems.

After battling through bouts of strep throat and bronchitis plus allergy concerns, impacted wisdom teeth and mild asthma on his own, Day says he’s ready to seek some answers for his on-going problems.

He was under the weather a fortnight ago in his return from injury at the Memorial tournament – just his second event since winning in February – where he tied 37th.

And while he claims to be fine at Pinehurst this week, multiple coughing bursts might tell a different story.

“I don’t know what it is but I’m not looking to make it an excuse,” said Day, who was tied second in last year’s US Open.

“But when you’re sick it does hurt your performance. Your equilibrium is out and it takes more energy to concentrate and focus.

“I guess I definitely have to look into it and see someone.”

With conditions extremely humid and energy-sapping, Day hopes the time off he took to rest last week will prove a godsend.

“US Open’s drain you mentally and they are physically demanding and it is so hot and humid here so rest is key in tournaments like this,” he said.

“But in saying that I like grinding it out – the more stress, the better. It’s not that I like stress, it’s just where I seem to perform.”

Almost to a man the Open field is talking up the importance of the short game this week, an element Day usually has under control.

His runner-up Open finish last year followed a second placing in 2011 also, including a record 45 holes in a row without a bogey.

This year his putting statistics are well off his usual standards.

“I am hoping the toughness of the course just kick starts the short game again,” he said.

“I’m looking forward to taking this course on. It is a good risk-reward golf course and it is fun to play but I don’t think you can be conservative enough in US Opens.

“It is better to play from fairways and while you can jag a lucky lie in the waste areas it is easier to hit the greens when you’re not in the junk.

“Even if you do have the best short game in the world these greens and this grass can frustrate the hell out of you.

“It is very grainy. The guy who gets up and down the most will win.”