Beer Flavors / Off flavors

I have been home brewing for 5+ years now, and also worked in commercial breweries. (I only mention this because i feel my sanitation and brewing procedures are fine.) My issue is that i have been noticing a weird foggy headed, unpleasant and abnormal headache feeling when i drink my home brews and I cant seem to make it go away. No this is not an overindulging issue, because even when i sample some fermenting wort from the primary, and only take a sip, the same issue happens.

Here are the facts.
-I think it is something i am doing in the Mash/Sparging process.
-I have taken wort from the brewery and pitched yeast and fermented/completed processing it at home WITHOUT the same issue.
-It happens even when I use different recipes/ingredients/yeast
-I have changed water supply and the same effect occurs
-Other friends homebrews do not have the same effect and i feel fine after drinking them
-It is not a contamination issue, most of my beers overall flavor are really good (like we all think, right)?
-I have made a batch by steeping grains and adding some extract and I dont get the same issues.
-The abnormal headache feeling will last for about 10-15 minutes after having just half a 12 oz beer.

Not sure what it is and any insights will be appreciated and helpful.
Thanks

For me I get a headache if I drink a beer with a high tanin concentration. It doesn't take much to give me a slight headache, sometime I don't even really taste it in the beer unless I'm "tasting for it" I'm sure you know from your experience that comes across as a somewhat astringent/bitter taste like tea that was steeped too long. That can happen if the both the temperature is above 165 and the pH is above about 6. The most common cause of that in home brewing is sparging too long. To avoid this I mash thin and sparge less. My efficiency may not be stellar because of it, but it is consistent.

It sounds like your problem is coming from your mash/mash tun. As mentioned it could be a tannin issue with your mash.

What is your mash tun made of? Any galvanized parts at all( a screw, nut, washer, etc.)? Any rust anywhere? Plastic that is not thermal resistant?

Yeah the pH might be an issue, along with oversparging. I actually used some acid malt in flanders red ale, and the issue seemed to not be there. Maybe I will try to add some phosphoric acid to the mash water, increase strike liquor and reduce sparging. I had been doing about 1.25-1.5 qrts/lb grist ratio, but maybe ill increase to 1.75, just to see. I do have some test strips but have not found them to be very accurate, will probably invest in a digital pH meter. Thanks for the help. Will let you know, i am brewing a dubbel tomorrow.

Changing the mash protocol didnt seem to change anything and the issue still exists. Mash pH as indicated by the test strips was 5.1 so that was well with range. Yeast (T-58) pitched at 70 degrees and fermented at 72 degrees. I am using a Igloo cooler with a stainless false bottom, and high temp hosing from morebeer connected to a SS ball valve with silicone o-rings. (I have also used SS as mash tun with all stainless fittings and it still happens.) High temp hose to runoff into the kettle. SS racking cane to siphon out of kettle into glass carboy. Oxygenated and pitched yeast. The other thing is that my girlfriend does not get the same reaction, and thinks the beers taste great. Not sure what to change.

Do you use any fining agents, yeast nutrients, etc. at home that you wouldn't use at the brewery? Maybe you have developed some kind of allergy to something you are using.