Someone pls tell me why this could have happened

Husband was taking fertilaid for a few months then went to visit family abroad for a month. He didnt take the vitamins during that month. Came back from his visit and a few days later at the end of August he got his first semen analysis:

Count 89 million

Motility 38%

Morphology 1%

He started back up on fertilaid and i also had him take 4 maca capsules, 2,000 mg vitamin C, coq10 200-300 mg, 500mg tribulus, and like maybe 2,000 mg ashwagandha daily. I know it sounds like a lot but according to some recent studies theyre supposed to takd more like 5g ashwagandha and 5g maca etc.

He got his 2nd SA done this thursday and the results were:

Count 27 million

Motility 46%

Morphology 2%

He has been stressed out lately but other than that nothing has changed in his daily habits. He didnt get sick. No antibiotics. Nothing. What the hell is going on here? Im thankful that motility and morphology went up bc that morphology was really scaring me but how could the count drop so low??? I understand that SA results change all the time but this drastic?

Also another question...how exactly do they calculate how much sperm is actually healthy and moving fast? With the 2nd SA for example do they take 2% of 27 million and get 500 something thousand and say that only 46% of THAT morphologically normal sperm are actually swimming the way they are supposed to? Im worried that IUI wont work because the count dropped so much.