Should I contact GP?

[GatOrHeet]

Had the whooping cough vaccination about a week and a half ago (pregnant) and I have now developed a large raised and hard, red lump on my arm where the injection was, about 10cm across which has slowly gotten bigger the past few days.

It is also very itchy and I can't sleep on that side because the arm is too sore still.

I otherwise feel fine in myself. I was expecting some soreness for maybe a few days afterwards but not sure if this is normal.

It's noticeable to the point where people have asked me what I've done to my arm.

Of course you should! That needs urgent medical attention.

Ring the GP or the clinic you got the vaccination in the morning. If you are otherwise well and it is not spreading up or down your arm then hopefully it's just a localised reaction at the injection site.
Injections in the arm I find tend to be more tender as there is usually less muscle than a hip jag. In saying that, you shouldn't be excessively sore, do phone in the first instance so someone can have a look to rule out any infection.

Apologies, 10cm didn't register in my brain when I first read your post. Ring first thing, your doctor or midwife will definitely take a look. Get someone to take some photos too for you just in case. Our surgery uses a system where you send 5 photos if it's a rash or reaction before calling you in and they'll treat you over the phone if able.

Thanks I'll ring them in the morning.

It's annoying as it's quite hard to catch on a picture, you can see redness but the lump is difficult to see not in person if that makes sense. You can definitely feel it if you run your hand across my arm and you can see it in RL. It's hard and raised and is quite large.

I hadn't really thought much about it other than telling DH it was still hurting to sleep on, until I visited family yesterday who didn't know I'd been for it and the first thing they asked when I came through the door was what I'd done to my arm. They said they thought I'd been bitten by something nasty. Then my mum said the same thing today.

Have left a message with the reception will see what they say!

My daughter had the same as a child, it was quite scary looking but it really was nothing to worry about.

We were told to speak to the pharmacist and they provided reassurance.

It'll be a reaction to the tetanus component.
That's why we only give 5 in a lifetime apart from needing to give it with the whooping cough vaccination. It'll go done in time, unless it's tracking redness up or down your arm, I wouldn't worry.