Continuous headaches and breathing trouble..!!

Hey guys,
My husband has been suffering from headaches and breathing difficulties for the past few weeks. He used to feel the same before, so he hasn’t consulted a doctor yet. Usually, he will be alright after a couple of days taking some painkillers and medicines prescribed by the doctors earlier. But this time he is not feeling better even after taking the usual medicines. I’m noticing that the same health issues are happening to him several times in a month. He is working in the forging industry and he might have to deal with various forging processes, heat treatment of metals and all. Did people working in the forging industry can cause these health problems? Because I have read that the carbon monoxide forming during the heat treatment process cause many health problems. I’m worried about his health. Is this regular occurrence of headaches and breathing trouble is the starting of something serious? I would be grateful for your thoughts on this.