Weird taste after a filter change

We recently changed our filters for the first time since we purchased the system last year. We got the person who installed the system change our filters since it's not that simple to do. After the change, the water doesn't taste and smell right. We ran the water as directed and then ran it twice on two different days. It's been 8 days now and it still smells and tastes weird. I'm very concern because I'm 8 months pregnant and was wondering if this "bad" water is going to harm the baby.
I need some answers because I know this guy who sold this system is going to back up his work. I just need a second or a third opinion.

Can you describe the taste? What did he use to sanitize the unit when he changed the filters?

What filter and what system are you using?

Thanks Alex and pawaterguy for replying. I have a whole-house GAC- carbon down flow FILTER/PURIFIER system, whole-house WATER SOFTENING/CONDITIONING system, and Water Factory Systems model SQC3 RO. This if the first time we changed the filters since we bought the system last year. At first I thought my cups were not washed well, since the water had a foul scent and a soapy, flat, and "not clean" taste. So I rinsed the cups and still it had that same taste and smell. Also, the RO line is linked to the refrigerator, which has a filter, and the water from the refrigerator tastes better then the water that is coming directly from the RO.

We were going to change it ourselves so the person who sold the system gave us instructions and a list of things we need to do. At the end, we just didn't have the time to change it so we got the company to do it for us. The person used 5.25% non-scented chlorine bleach (same used for clothes) to clean the system. Did they do it wrong? Did they miss a step? Did they use the wrong cleaning solution? I'm very concern because I'm 8 months pregnant and I was drinking this water thinking it was just me tasting this weird taste. We bought the system because of health benefits, especially being pregnant, but now I'm just worried about my baby.

If the RO system was disinfected and the filters were changed, I would be sure that the system is fully flushed out. Especially if the membrane was also replaced.

The new membranes will have a preservative that needs to be flushed by dumping the first 2 tank fulls of RO water. This may help.

Maybe pawaterguy has another recommendation as well.

I did flush the RO as directed and then I had flushed it 3 more times on three different days. It still has that weird smell and taste. Is there a missing step? Was all 3 filters needed to be changed?

I doubt the membrane was replaced already...but anythings possible. In the cases I have run into where an off taste occurred it almost always ends up being resolved by replacing the storage tank. That's assuming it's not just simply chlorine residual. Most times it's a musty type of odor described by customers though not always. Hope that helps.