The phrase "altered constantly" is correct and usable in written English.
It can be used to describe something that is being changed or modified on a continuous basis.
Example: "The software is altered constantly to improve its performance and fix bugs."
Alternatives: "changed continuously" or "modified regularly".
Do you notice the altered feeling constantly or only when touching the area, or chewing, or talking?
The brain is directed by, but also directs gene expression, influencing and altering it constantly.
The impressionable Numan constantly altered the sound, absorbing and exploring.
This season he has constantly altered his selections and while injuries have played their part, some of the tinkering has been unnecessary, bordering on panicked.
The neighbourhood itself appears to have barely altered; I'm constantly stumbling over the houses I visited and the parks where I played.
What has constantly altered is the political context, the series' peaks unsurprisingly coinciding with the fieriest times at Westminster: the rises and falls of Thatcherism and Blairism, the Gulf and Iraq wars, the periodic attempts to reshape the United Kingdom and the European Union.
The firm, Solid Objectives — Idenburg Liu, came up with an interconnected system of poles and bungee cords that is constantly altered by human action and environmental factors like rain and wind.
On Aug. 29, 1975, a new junta was formed, headed by Gen. Francisco Morales Bermúdez Cerrutti, former minister of finance and economy, and Peruvian policies were constantly altered as repeated changes in the cabinet took place.
The continual intrusion of new groups into the Plains first Indians, then whites and the introduction of new weapons constantly altered the balance of power and kept the region in a state of belligerent turmoil.
