Feeling really emotional- thinking about the worst things

To start off I had the implant put in about 3/4 weeks ago so I think this is the reason I’m emotional but the last week or so my brain keeps thinking the most horrific things which are starting to really upset me. I watched a documentary about ww2 the other day and there was a scene about a little girl, I won’t go into detail but all I could imagine was it being my daughter and it made me so sad I actually cried. Ever since then I just keep thinking of bad things happening to my daughter and it literally makes me shudder and brings tears to my eyes and every time she cries it makes me want to cry because I don’t want her to be sad. What can I do to stop thinking this way? It’s starting to take a toll on me, I have cried every single day because of this. I’m finding it so hard :(