My Maltese dog has been acting strange the last 3 nights. She has been restless, walks back an forth, wants to near me at all times, wants to be held and petted. Last night I noticed she was panting and tonight she was shivering when I picked her up. Should I be concerned?

Yes u should clearly something or somebody is putting her in that position so that's probably 1 of the resones or she feels like she needs more than enough of attantion. But u might want to take her to a vet

Is she spayed?

If not, when was her last heat cycle?