When do off flavors show up?

Hi all! I have been using this forum since day 1, but I unfortunately finally found a reason to post. This one is really bothering me.

My first 2 batches have developed this identical off flavor that is hard to pin down. I originally thought metallic, then medicinal, but not fruity. One LHBS guy said acetaldehyde, not overly medicinal. Other LHBS guy said he didn't get any acetaldehyde, but didn't know what it was. Finally, my wife said "soapy". The beer is far from undrinkable, but it's getting hard to enjoy it.

Both batches are American Wheat (OG=1.042), LME (all at start of boil), partial boil using tap water, fermented with Safale US-05. First batch spent 2 weeks in primary and now 8 weeks in bottle (@70F). Second batch spent 3 weeks in primary and now 4 weeks in bottle (@70F). Both pitched around 75F-78F and stored at 68F (ambient). Both reached final gravity (about 1.01) and were carbed with 2/3 cup dextrose if I remember correctly. Used starsan to sanitize.

Both tasted really good at bottling time (especially the second, I added some extras to the boil). Both tasted even better around 2 or so weeks after bottling. After that, they both got the weird taste that has worsened (or become more noticeable) over time.

In my opinion, it has to be from:
1. Infection
2. High fermentation temps
3. Chloramine

Infection seems unlikely ... new equipment, no sanitizing blunders to my knowledge, no gushing bottles, the off flavor isn't terribly overbearing, and it happened to 2 batches. Could an infection take over that late in the game? High fermentation temps could be possible, but wouldn't the flavors be strong at bottling time and potentially mellow with age? I don't know the exact chemical reaction undergone with chloramine to produce off flavors, but any reason that would show up weeks after bottling and not right away?

Any info on my specific situation or the timetable for off flavor development would be greatly appreciated.

From my limited knowledge you pitched high for sure and it could have fermented a little too warm. I generally assume my beer is about 3 degrees higher than what it reads so yours would be 71 which is on the high end of the yeasts limits. That's the extent of my input

This article may tell you a bit about the off flavors but medicinal is likely from chlorine or chloramine in the water. Your other off flavors that you get from pitching high might be masking that and confusing your taste.

http://www.brewgeeks.com/the-life-cycle-of-yeast.html

I don't want to say this because I don't care for fruit and vegetables being added to a glass of beer. In this case a slice of lemon may mask the off flavors. Drink the batch a soon as you can before the off flavor becomes to strong.

Thanks for the replies. I'm aware of the less than perfect beginner practices, and the potential origin of different off flavors. I'm also not looking for a way to make my beer drinkable now, it is what it is ... I want to make good beer in the future. I can walk to Yards or PBC if I want drinkable beer now . I find the "when" for these off flavors as a more helpful discussion for me and beginners alike.

I spent the last hour and half reading this thread. https://www.homebrewtalk.com/f14/8-batches-i-still-cant-shake-off-flavor-104841/

Sounds very much like my problem, but his water did not have chloramine, mine certainly does. Anybody know details about Philadelphia city water? Maybe the water is alkaline? I just bottled an AG batch, and I will be treating ALL of my water next time with campden tablets so hopefully one of those solves the problem. Does the claim that chlorophenolic off flavor doesn't occur until after carbonation have any truth to it?