Please help - unhappy baby who can't be put down.

[LittleOneMum]

Please post if you feel you have any tips or answers for me.
I have a DS (3) and a DD (4 months). I was pretty ill when my DD was born and she was looked after by my Mum for the first few weeks of her life.
Since I started to look after her again, she has had real difficulties being put down by herself during the day. I will try to describe how she is, and please tell me if it seems to you to be (a) normal (b) abnormal and if so what I can do.
Basically if we are out and about in the buggy she is fine. But if I put her on the bed or in her gym or in her chair for more than a few minutes she starts to scream. This makes it really difficult to look after my 3 year old or do anything like even make breakfast etc. It also totally stresses out my toddler, although I have explained that babies do cry and it is normal really.
Once she is picked up and walked around she is fine. I dont think it can be colic at this stage, it doesn't get worse at any stage of the day and isn't she too old?

Thank you so much for your time.

Sorry but I gave my baby constant attention in the early months. Now at nearly 1 he's just fine - walking, plays happily alone etc. He has his clingy moments but that's when he's ill/teething or nervous. Seems a bit mean to just leave him to it when he obviously needs me.

I think what I've realised from this thread (and I am genuinely grateful for everyone's posts) is that regardless of the decision you make about leaving your child/carrying them around all day, they all pretty much turn out all right in the end. As such, it is just a question of deciding what works for you and your family.
Having thought about it, it seems to me that middle ground is the way forward for me, I will not carry DD in a sling all day, but equally I will not let her cry for great chunks of time. I will carry her around as much as she needs it but will try to leave her for slightly longer in the gym etc each day. Ultimately she's my baby and I want to comfort her and I will. As you all say, she'll grow out of it.
Thank you all though for making me realise that it happens with other babies and making me feel less alone! x