I really don’t know what to make of this hugely popular FTSE 100 second income stock. I don’t know if it’s a brilliant British blue-chip having a bad run, or a bad blue-chip that’s getting what it deserves.

The one thing I know for sure is that the GSK (LSE: GSK) share price hasn’t performed how I expected when I bought the pharmaceutical stock at the start of this year.

And now I’m asking myself three questions. Should I take advantage of its recent troubles to buy more?Should I sell and move on? Or hold and hope for the best?

The GSK share price is a nightmare

I have distant memories of the days when – in its former incarnation as GlaxoSmithKline – this was every income seeker’s favourite UK stock. At least, that’s how it felt at the time.

Investors bought it for its solid yield, which typically hovered around the 5% to 6% mark, and the happy expectation of share price growth on top. Then gradually, they began to worry about the drugs pipeline, that was looking a bit thin as former blockbuster treatments went off patent, and new ones were slow to arrive.

CEO Emma Walmsley, appointed in 2017, set to work putting that right but had to sacrifice dividend growth to do it. With shareholder payouts frozen at 80p per share and the stock refusing to rally as hoped, investors drifted away.

Hiving off consumer arm Haleon in 2022 didn’t bring back them back. I thought GSK looked good value in January and dived in. There were more problems just around the corner.

A decent dividend yield at a bargain price

My shares slumped over the summer when a US class action claimed that a discontinued version of its blockbuster heartburn treatment Zantac caused cancer. The shares rallied when most claims were settled in a $2.2bn payout on 9 October.

But within a month they were crashing as Donald Trump won the US presidency and appointed controversial vaccine sceptic Robert F Kennedy, Jr, as US Health Secretary. Trump is taking on big pharma.

The GSK share price is now down 24.6% in the last six bumpy months, although it’s still up 5.95% over the last year. It looks terrific value though, trading at just 8.63 times earnings. In the old days, it was routinely valued at 15 times.

Plus the previously underwhelming yield has jumped to 4.63%. So to my three questions. Should I buy more? Answer: no. There’s now a big question mark over the sector while we wait to see what Kennedy does. Gambling on buying more would be a blind bet.

Should I sell? I’m sitting on a 20% loss and I’m not too happy about crystallising that. A lot of bad news has been priced in, and maybe things won’t be as bad as they look.

Which brings me to the final question and yes, I’ll hold. Investing is a long-term game and things may get better at GSK. Although being honest, I wish I’d never bought it at all. There are better passive income stocks out there.