for a long time vs Since a few days

Some examples from the web:

• Oct 27, 2011 ... Which preposition is correct and what is the difference in meaning if any? I went to the gym, something I haven't done for a long time. I went ...
• In formal contexts, if something bad or unpleasant continues for a long time and never improves, you can say it happens unremittingly.
• How to use "for a long time" in a sentence? ... These sentences come from external sources and may not be accurate. bab.la is not responsible for their content.
• "I felt for a long time like everything beautiful in me had been taken out": Women's suffering, remembering, and survival following the loss of child ...
• Mar 21, 2023 ... 'I cried for a long time': Black hair stylist's dream crushed by racist neighbor. Angel Pittman says her dream to create a mobile hair salon ...
• 2 days ago ... He gets better and better every year, and I really hope Alex is here for a long time.” The Steelers have made some moves this offseason to free ...

Some examples from the web:

• Since a few days ago, she keeps following me.
• Mr President, not everyone in Zimbabwe will be happy about today's debate, since in a few days' time, 18 April will be Independence Day in Zimbabwe.
• Although his nomination has been known since November, just a few days prior to his nomination hearing in the committee, information was spread about Mr Fazakas' possible collaboration with the state secret police.
• They spent a few days since I read the diary.
• I guess it has been a few days since I've had any fun.
• July 2. passed a few days since I started practicing the spells of the diary.
• It hasn't even been a few days since the Soviets shot down the KAL plane!
• In the past few days since my in-laws brought me home, I have endured... more pain than I thought humanly possible.
• Let us see if you can manage to be more grown up, since in these last few days, I have unfortunately heard remarks such as 'Parliament is not a playground.
• Not since his last text message a few days ago...
• My trial ends in a few days, and my acquittal has been evident since day two.
• My trial ends in a few days, and my acquittal has been evident since day two.
• A few days later, my best friend, a guy that I've known since I was 10, they said he committed suicide.
• Usually I would just contact my own doctor for the pills, but since I wasn't planning on being back in the States for a few days...
• But since the contest is in a few days and you're a battle-tested Army choreographer...
• I been laid up since I found this hollow a few days ago.
• A person murdered a few days ago was the twenty-fifth Portuguese victim since the beginning of the year.
• It was my intention to go a few days here in Palma... But... since my presence bothers you, take out the noise.
• So did I and I'm sure she will, but I haven't seen him since he left for Manchester a few days ago.
• Matthew and William went out on a patrol a few days ago and they haven't been seen since.