On April 15, 2009 Mr Nisbet, 47, felt sick at work and thought he was going to faint, and was rushed to hospital.
A doctor who saw him that morning spoke on the fourth day of Milner's High Court murder trial in Christchurch that he presented at the city's main hospital complaining of an insect bite.
His wife was with him, and he "appeared anxious", Dr Shamil Haroon told the jury via video link from England this morning.
The Crown alleges that Milner was determined to kill her husband and cash in a $250,000 life insurance policy.
It's alleged she plotted the best way to do it, asking friends and workmates for views on poisoning methods, and offering to pay a hitman $20,000.
The Crown alleges she killed him, most probably by slipping up to 50 crushed tablets of anti-histamine drug and sedative Phenergan into his food, then smothering him with a pillow before faking his suicide.
Dr Haroon noted that Mr Nisbet had been weeding his garden two days before he saw him on April 15 when he thought he was bitten by an unknown insect.
He reported pain and swelling on his shin and knee the next day, before feeling weak and nauseated that evening.
Hospital testing found little wrong with Mr Nisbet, who had a clear chest, normal pulse rate, no shortness of breath, and no visual symptoms, while neurological exams appeared normal.
Mr Nisbet said he'd felt dizzy, nauseous, and hot and cold at work, feeling like he was going to faint.
He and Milner admitted he was "of a nervous disposition", and had experienced a similar reaction an insect bite while on holiday in Australia the previous month.
Dr Haroon said there was a small, circular, slightly raised, red area around his shin but had made no direct note of a sting or bite mark on his skin.
Otherwise, he could find nothing wrong with Mr Nisbet and so sent him home later that morning.
The Crown alleges that once they got home, Milner went out and bought more of the drug Phenergan at a pharmacy under a false name.
She's accused of giving him more of the drug, making him feel unwell, which resulted in another rush to hospital.
The trial, before Justice David Gendall, continues.