33M: Lightheaded and racing heart since starting desvenlafaxine (normal adjustment or stop?)

33M, 5'11, 238 lb. No chronic medical diagnoses other than anxiety. Non-smoker. Alcohol 0 to 2 drinks a week. Caffeine 1 to 2 coffees a day. No recreational drugs.

Meds/supplements: started desvenlafaxine 50 mg once daily six days ago. This is the first antidepressant I've ever taken. No other prescription meds. I take a multivitamin a few days a week and occasional ibuprofen. No decongestants.

Why I was started: my GP put me on it mainly for anxiety and panic episodes that have been coming back.

Symptoms: since day 2 I have had episodes where I feel "wired" and shaky, my heart races, and I get lightheaded like I might faint. I have not actually passed out. It happens randomly but seems worse in the late afternoon and evening when I am trying to relax, gaming, or working on my laptop. I also get some nausea, sweating, and trouble falling asleep. No chest pain and no fever. I can walk around but I feel off.

I checked my pulse once during an episode and it was around 110 to 125 while I was sitting. My usual resting pulse is in the 70s. Blood pressure at home was 128/78 during a calmer moment. I am not having suicidal thoughts.

Questions:

1. Is this a normal early side effect of desvenlafaxine, or could it mean I should stop it and contact my doctor right away?

2. What red flags would make this an urgent care or ER situation versus something I can wait to discuss with my GP?

3. If this is an adjustment period, how long do those "activated" feelings usually last?

I don't want to overreact but this has been pretty unsettling. Any advice on what is normal versus concerning would be appreciated. Thanks.